Calculation of the refractive indices and relative densities in homologousseries of organic compounds

It was shown that the dependences of the refractive indices n(D)(20) and re lative densities d(4)(20) for normal Linear homologues of a series on the n umber of carbon atoms in the molecule n(C) can be approximated by the fract ional power function y = an(C)(k) + b (k = -0.899 for n(D)(20) and -0.850 f or d(4)(20)). The limiting values of these functions at n(C) --> infinity, which are the same for all homologous series, correspond to a hypothetical compound (aperant) characterized by (n(D)(20))(infinity) = 1.475 +/- 0.003 and (d(4)(20))(infinity) = 0.857 +/- 0.008. The most important practical co nsequence of this concept is a new method for calculati ng the refractive i ndices and relative densities of members of a homologous series from the co rresponding constants for any other member of this series. This method is b ased on the relationship P-x (n(D)(20) or d(4)(20)) = (P-ref - b)(n(C), x/n (C, ref))(k) + b, where b = 1.475 and k = -0.899 for n(D)(20) and b = 0.857 and k = -0.850 for d(4)(20). The form of the equation is new, and the accu racy of calculations is unique (similar to0.06% for n(D)(20) and 0.12% for d(4)(20)).